Mercury contact switch



April 11, 1933. J, N. McTWlGGAN MERCURY CONTACT SWITCH Filed Dec. '7; 1931 2 Sheets-Sheet 1 INVENTOR Jame; MTw1g9qm flaw a, M

' ATTQRNEY Patented Apr. 11, 1933 UNITED STATES um 11. uermeem, or mm: mm) auras RAVI MERCURY CONTACT SWITCH Application filed December 7, 1931. Serial No. 510,550.

(61m THE ACT OF MARCH 3, 1883, AS AMENDED APBIL 30, 1828; 870 0. G. 757) I This invention relates to a mercury contact electric switch, and more especially to one that is enclosed to keep out moisture and explosive gases, and is constructed to withstand considerable pressures to adapt it to use under water. i V

The ob'ect of my invention is to' provide a switch t at will positively eliminate danger of igniting explosive gases when used where such gases are present andthat may be used on the exterior of submarines to the greatest depths at which such vessels operate.

With the above and other objects in view, the invention consists in the construction,

combination and arran ement of parts as will be described more ully hereinafter.

Reference is to be had to the accompanying drawings forming a part of this specification, in which like reference characters 1n- 'dicate corresponding parts throughout the several views, and in which: I

Figure 1 is an exterior perspective view of my invention;

Fi re '2 is a sectional view taken along the longitudinal axis thereof; with the device in the off position;

Figure 3 is a view in the same plane as Figure 2, but in the on position, with parts omitted;

Figure 4 is a detail sectional view on the line 44, Figure 3;

Figure 5 is a transverse sectional view on the line55,Figure 2; and, p a

Figure 6 is a detail view of'the contacting faces of the se arator disks.

It is often esirable or necessary to have electric switches located in places where there is an explosive mixture in the air, formed by finely divided dust of carbon,

flour, or other combustible substances, or

where there is an explosive gas, such as hydrogen that has been evolved by the charging of storage batteries.- It is also desirable to have on the bridges of submarines a switch that will withstand immersion to the greatest depth at which such vessels operate without leaking under the pressures there encountered. The present invention has been designed to meet the requirements of such conditions.

The case 7 is of metal with a substantially solid end 8 and a cap 9 to form a closure for the other end thereof, there bein a handle 10 afiixedto the cap to be graspe to rotate the case. If desired, a suitable gasket may be used between the inner face of cap 9 and the edge of case 7 that fits therein topmake a tight joint. Mounting plate 11 has in it countersunk holes 12-to receive securing means to hold the switch firmly upon. any convenient supporting member. The edge of plate 11 is rabbetted to form a flange 13 of the same diameter as flange 14 on the adjacent end of case 7, the two flanges being seated within a radially split coupling ring 15 that is U- shaped in radial cross section. Handle 16 is secured on case 7 to serve as an additional means of operating the switch. Plate 11 has indentations 17 on its inner face to receive detents 18 actuated by sprin s 19 in recesses 20 in end portions 8, there eing a pair of such indentations disposed to lock the.device in the on position and another pair for the ofi position. A leak proof closure of the recesses 20 is efiected by plugs 21 screwed 75 thereinto.

In case 7 are telescopically interfitting members 22 and 23 made of suitable insulating material with chambers 24and 25, respectively, formed therein in registry with each other. -Electrodes 26 and 27 are disposed in chambers 24 and 25, respectively, to cover the end walls of the chambers, the threaded bolts 28 extending out fromthe. electrodes serving both as securing means to hold the'electrodes' in position and as binding posts for the conducting wires that make the external connections with the switch, the wires being threaded through holes29 and passing to the exterior in ca le 37 through a packinggland 36 in the threaded aperture 30; A quantity of mercury 31 is placed .in chambers 24 and 25 (whichmay be partially evacuated if desiredto prevent oxidation of the mercury byl any sparking that may occur) and as t e electrodes 26 and 27 are coextensive with the end walls of the chambers they will always be in contact with the mercury in an rotational position of. the device, so that t e circuit cannot break at the lating material, are clamped between shoulder 33 on member 22 and the edge of member 23. Each separator has an aperture 34 opening from one face into an arcuate groove 35 I adjacent chamber,

on the opposite face. The separators are assembled with the grooves 35 in registry,

which makes the. apertures 34 offset by a distance equal to thelength of groove 35 when the disks are assembled, the two apertures and grooves cooperating to form a passage of the shape shown in Figure 4 fromchamber 24 to chamber 25.

When the parts are in the position shown in Figure 2 the insulating separator disks efi'ectively isolate the mercury in one chamber from that in the other, but when rotated to the position shown in Figure 3 mercury enters apertures 34 and flows into grooves 35 and forms a continuous path of mercury from one chamber to the other, thus placing electrodes 26 and 27 in electrical connection with each other and closing the circuit throu h the wires connected to binding posts 28. 7 he mercury will flow into the orifice 34 that first passes through the surface of the mercury when the circuit is being closed, but

due to the tortuosity of the passage tot'he opposite side of the other disk the interior of the devlceis somewhat evacuated. Inasmuch as the mercury 1s always 1n contact with electrodes 26 and 27 there can not be any sparking at the electrodes and hence the are preserved from disintegration.

en installed for use, the plate 11 is fixed to a support, and to operate the switch entire case 7 and all the parts therein are rotated by means of handle 10 or handle 16,'the case being free] rotatable in ring 15. From the off osition shown in Figure 2 the device must be rotated 180 to the position shown in Figure 3 to close the circuit, in which position the mercury forms a continuous body from chamber 24 to chamber 24 through apertures 34 and. grooves 35. The circuit is broken by a reverse rotation of sufiicient angular magnitude to raise one of the apertures 34 from the body of mercury 31 in the the movement being continued back to the off position so that'all passage 35 will normally not be filled by the time the the mercury so drained is supplied by that within the said passage, the final break of the circuit will occur at the juncture of the above mentioned stream and its source of supply, that is, disks 22; Thus the breakin of the circuit, as well as the making thereo occurs within disks 32, and any sparking at either of these times is confined-to the space inside the disks and oxidation of the mercury eliminated.

It will be understood that-the abovedescription and accompanying drawings comprehend only the general and preferred emodimcnt of my invention, and that various changes in construction, roportion and arrangement of parts may e made within the scope of the appended claims, without sacrificing any of the advantages of my invention. The herein described invention may be manufactured and used by or ment of the United States for governmental purposes without the payment of any royalty thereon.

I claim: 1. An electric switch of the mercury contact type, comprising a case having a sub-. stantially closed end and an open end, recesses in said closed end, a spring actuated detent in each of said recesses, a plug to close an end of each of said recesses, a peripheral flange around said closed end, a peripherally flanged mounting plate adjacent said closed end, a coupling ring U- shaped in radiallcross section disposed to embrace both said flanges in relatively rotatable relation, indentations in said plate to receive said detents, telescopically related members of electrically insulating material in said case, chambers in said members disposed to register with each other, an electrode in each of said chambers substantially covering the end Wall thereof, an element extending outwardly from'each of said electrodes to serve as a securing means and a binding post, a passage in each of said members extending from adjacent said binding post elements to points adjacent an aperture in said case, a packing gland in said aperture, insulating separator disks disposed in face to face contact with each other transversely of said chambers and clamped between said members, each of said disks having an arcuate groove on the face thereof'in contact with the other disk and the said groovesregistering with each other, there being an aperture through one of said disks opening is practically into one end of the passage formed by said the mercury within the passage to I for the Governregistering grooves and a second aperture through the other of said disks into the other end of said passage, a closure for the open end of said casing, 'means manuallygraspable to rotate said casing, and a body of mercury in said chambers.

2. An electric switch of the mercury contact type, comprising a case closed at one'end, telescopically related members of insulating material'in said case, chambers in members disposed to register with each other, an elec-. trode in each of said chambers substantially covering the end wall thereof, an element extending outwardly from each electrode to serve as a securing means therefor and as a binding post, a passage in each of said members extending from adjacent said binding post elements to points adjacent an aperture in saidcase, a packing gland in said aperture, insulating separator disks disposed in face to face contact with each other transversely of said chambers and clamped between said members, each of said disks having an arcuate groove in the face thereof in contact with the other disk and the said grooves registering with each other, there being an aperture through one of said disks openin into one end of the passage formed by sai registering grooves and a second aperture through the other of said disks into the other end of said passage, a closure for the open end of said case, means for rotatably mounting said case, a body of mercury in said chambers, and means graspable to rotate said case.

3. An electric switch of the mercury contact type, comprising a rotatably mounted case, chambered insulating members disposed therein with the chambers in registry, lnsulatin separator means disposed transversely 0 said chambers between said members, said means having a passage therethrough longer than the distance between the faces of said means, a body of mercury in said chambers, an electrode in each chamber disposed to be in contact with the mercury therein in all rotation positions of the device, binding posts connected to said electrodes, and means for making vapor and ed case, chambered non-conducting members therein adapted to contain an electrically conducting fluid, insulating means disposed.

transversely of said chambers between said members having a passage therethrough to permit contact between of the fluid in one of said chambers with that "in the other thereof in one rotational position of the device but to prevent such contact in another rotational position thereof, means in said chambers to form electrical contact with said fluid, in all rotational positions of the device and means to make connection between said last mentioned means and the exterior of the device.

6. In an electric switch, a rotatably mounted body having space therein to contain an electrically conducting fluid, insulating means to divide said fluid into two masses in one rotational stage of said body, said means having through it an indirect passage to per- -mit said fluid to unite into one mass at another rotational stage of said body, an elecbe in contact with the fluid at all times, and

means to make connection between said elec-.

trodes and the exterior of said body.

7. In an electricswitch, a rotatably mounted body having space therein to contain an electrically conducting fluid, insulating means to divide said fluid into two masses in one rotational stage of said body, said means having in it an enclosed space forming part of a .tortuous passage through said means, and means to make connection between said fluid and the exterior of said body.

pressure proof connection with said binding posts from the exterior of the device.

4. In an electric switch, a rotatabl mounted case, chambered insulating mem rs disposed therein with the chambers in registry, insulatin separator means disposed transversely 0 said chambers between said members, there being a passage through said means with an opening on each face of said means and the openings being angularly offset with respect to each other, an electrode in each chamber substantially coextensive with trode on each side of said means disposed to ios , the end wall of the chamber, and means for I making connection with said electrodes from the exterior. 0

5. In an electric switch, a rotatably mount- 

